How Diesel Power Products Took Control of Its Fitment Search on Shopify Plus

Diesel Power Products runs a deeply customized Shopify storefront for diesel truck performance parts, a business where fitment accuracy and core charges matter as much as speed. The site’s advanced search, fitment, and upsell systems were powerful, but they had been built and operated by a previous agency on external infrastructure the business did not own or have documented.

The biggest risk was the search and fitment stack. Vehicle filtering ran on an external Elasticsearch cluster and a manually generated lookup file, both controlled by the prior agency, with no documented hosting, access, or sync process. If any piece went down or was decommissioned, vehicle-specific product listings could simply disappear, and the business had no clear way to maintain, audit, or replace it.

Diesel Power Products needed to take ownership of its own stack, reduce that dependency, and improve day-to-day findability and reliability without disrupting a storefront that customers rely on to find parts that fit their exact truck.

Fyresite, as a Shopify Plus Partner, was brought in to take over the account and stabilize it. The work was planned as a careful takeover, documenting and securing the external infrastructure, hardening the theme, and reducing the business’s reliance on systems it did not control, all without interrupting daily revenue.

The centerpiece was replatforming vehicle fitment search. Instead of hardening a black-box Elasticsearch integration owned by another agency, Fyresite rebuilt search on Algolia, tuned specifically for diesel Year/Make/Engine fitment, and built a custom pipeline to index Shopify product, variant, and fitment data directly. This gave Diesel Power Products a search experience it owns and Fyresite can maintain and extend.

Fyresite also rebuilt the core charge feature that governs deposits on remanufactured parts, moving it onto a cleaner custom structure with configurable deferral periods, correct multi-state tax handling, and an admin workflow the operations team can manage without a developer. Alongside that, the team hardened the inherited theme, moving exposed keys out of theme files, addressing security and performance issues, and stabilizing the Google Shopping feed.

The result is a storefront the business finally controls, with faster, more relevant fitment search, a maintainable core charge system, and a documented path off the prior agency’s infrastructure. Search relevance has already improved noticeably, and the remaining stabilization work is mapped into a clear roadmap.